Liquefaction Potential Evaluation Based on Rayleigh Wave Investigation and Its Comparison with Field Behavior

A simplified method is presented for evaluating liquefaction potential of sand deposits using shear wave velocity. Effectiveness of the proposed method is evaluated through field tests at 17 sites in Niigata city where field performance during the 1964 Niigata earthquake is known. A modified version of steady state Rayleigh wave method is used in which the amplitude ratio between vertical and horizontal ground surface motions can be measured in addition to the phase velocity. Based on the measured phase velocity vs. wavelength relationship, shear wave velocity profile is determined using an inverse analysis. The liquefaction potential of each site is then evaluated using the shear wave velocity. The estimated results are reasonably consistent with the actual field behavior during the earthquake, indicating that the proposed method is effective

Considerations to Damage Patterns in the Marina District During the Loma Prieta Earthquake Based on Rayleigh Wave Investigation

Rayleigh wave investigation is made in the Marina District to study geotechnical factors controlling the damage patterns in the Loma Prieta earthquake. A portable system has been developed for determining a Rayleigh wave dispersion curve based on the measurements of artificially induced ground vibration or microtremor. Five sites are selected along a line crossing the hydraulic fill zone in which structures and/or buried utilities were significantly damaged. An inverse analysis on the measured dispersion curves results in a cross section of shear wave velocity profiles in the District. Site amplification and liquefaction potential of each site are estimated and discussed based on the Vs-profiles. It is shown that soil liquefaction is likely to have occurred throughout the fill zone, and that the predominant period of ground motions in the zone of structural damage is longer than and closer to the natural period of structures with soft first story than that in the non-damaged zone. These results appear to be consistent with the damage patterns in the District, indicating that the proposed investigation is effective for seismic zonation

Preliminary Report on the Geotechnical Aspects of the Philippine Earthquake of July 16, 1990

The Philippine earthquake of July 16, 1990 (MS = 7.8), of which epicenter is about 100 km north of Manila city, was one of the most costly single natural disasters in Philippine history. The loss of life of over 1,600 persons resulted. Extensive damage to buildings, roads, embankments, natural slopes, and bridges was observed in a widespread area of approximately 20,000 square kilometers. One of the major causes of the damage was liquefaction of various sandy soils including artificially fills, alluvial deposits of river delta, and sandbars. This paper presents a preliminary overview of damage aspects of the earthquake, with emphasis on liquefaction-induced damage of various structures

Japanese Encephalitis Virus in Meningitis Patients, Japan

Cerebrospinal fluid specimens from 57 patients diagnosed with meningitis were tested for Japanese encephalitis virus. Total RNA was extracted from the specimens and amplified. Two products had highest homology with Nakayama strain and 2 with Ishikawa strain. Results suggest that Japanese encephalitis virus causes some aseptic meningitis in Japan

Economical Estimates of Oxygen Uptake as a Function of Gait Parameters for an Ambulatory Monitoring System (携帯式モニタリングシステムのための歩行パラメータ関数としての酸素摂取量の実用的予測)

雑誌掲載版酸素摂取量(VO2)、歩行速度、歩数及び歩幅の関係を示す経験式を得る目的で、健康若年男性7名を対象に、水平トレッドミル上で16.7m/分から131.7m/分まで毎分5mの割合で加速歩行、106.7m/分の5分間歩行から毎分5mの割合で16.7m/分まで減速歩行させ、その間のVO2及び歩数を記録し、更に歩く速度と歩数から歩幅を算出した。歩行速度に対するVO2の変化は緩徐な加速と減速の間のVO2応答の平均値によって算出でき、運動テストを時間と費用の面で改善できることが示された。VO2予測値は歩行速度の関数として正確に二次方程式によって示され、更に歩数と歩行速度との密接な関係を用いれば、VO2もまた歩数の関数として表すことが可能である